update foreign key using entity framework - entity-framework

Question

i am trying to update foreign key in a table named(Friendship).The foreign key is of the table named(FriendshipStatus) the problem is that all the values are updated except the foreign key. I m using code first approach.
Friendship Class
public class Friendship
{
public int Id { get; set; }
public User UserOne { get; set; }
public User UserTwo { get; set; }
public FriendshipStatus Status { get; set; }
public User ReqSB { get; set; }
public RelationType RelationType { get; set; }
public Relationship Relationship { get; set; }
public DateTime FriendshipDate { get; set; }
}
FriendshipStatus class
public class FriendshipStatus
{
public int Id { get; set; }
public string Name { get; set; }
}
Here is the code for update
using (context)
{
Friendship f = getFrienshipRecord(u1, u2); // get single record from db which is to be updated
if (f != null)
{
Friendship ff = new Friendship();
ff.Status = new FriendshipStatus() { Id = 2}; //actually wants to update this this field
ff.Id = f.Id;
ff.FriendshipDate = DateTime.Now;
context.Entry(ff).State = EntityState.Modified;
context.SaveChanges();
}
}
The above code changes datetime but it does not change foreign key.

Answer 1

This is the technique I use for updates that include a child. First, I like to expose the Foreign Key as part of the parent. If you name it FriendshipStatusId, EF will make the association automatically or you can add an annotation or fluent code if preferred:
public class Friendship
{
public int Id { get; set; }
public User UserOne { get; set; }
public User UserTwo { get; set; }
public int? FriendshipStatusId { get; set; } // optional FK
public FriendshipStatus Status { get; set; }
public User ReqSB { get; set; }
public RelationType RelationType { get; set; }
public Relationship Relationship { get; set; }
public DateTime FriendshipDate { get; set; }
}
Now you can do your update by simply fetching the entity (which puts it under tracking) and updating the FK:
using (context)
{
Friendship f = getFrienshipRecord(u1, u2); // get single record from db which is to be updated
if (f != null)
{
f.FriendshipDate = DateTime.Now;
f.FriendshipStatusId = 2;
context.SaveChanges();
}
}
Note that if you add the FK you may need to do a migration or regenerate your database because the EF default might be something like FriendshipStatus_Id.